Clark in Chem. Rev. 80, 429 (1980) includes in a discussion of the fluoride ion as a base in organic synthesis a review of organic and inorganic fluoride sources. Many of these have limited or no solubility in organic solvents and are difficult or impossible to maintain in the anhydrous state because of their hygroscopic nature.
Farnham et al. in J. Am. Chem. Soc. 103, 4608 (1981) discuss structural aspects of the anionic pentacoordinate silicon compounds of the formulae ##STR2## Perrozzi et al. in J. Am. Chem. Soc. 101, 1591 (1979) disclose similar pentacoordinate silicon compounds of the formula ##STR3## wherein R is methyl or phenyl.
It is an object of this invention to provide an anhydrous, nonhygroscopic, thermally stable, pentacoordinate silicon compound which can provide a fluoride, cyanide or azide anion. Another object is to provide such an anion source which is useful as a catalyst or cocatalyst in polymerization systems. Still another object is to provide a polymerization system utilizing the aforesaid anion source. A further object is to provide a process for polymerizing methyl methacrylate by means of the aforesaid anion source. Another object is to provide such an anion source which is soluble in commonly used organic solvents. Other objects will become apparent hereinafter.